Part of the process of building and maintenance of software systems is the testing of the system against defined requirements. Model-based testing systems utilize an instance of a software system under test in combination with a model of the system. The model is arranged to perform in accordance with the expected behavior of the software system under test. A set of tests is provided in combination with a set of checking rules for testing the behavior of both the software system under test and its model. One problem with such model-based testing systems is that their effective use involves detailed understanding of the rules and corresponding model.